DroolinFool

Hi All,

My W209 (2004 CLK320) has a strange sort of clanging noise when driving over drains/speed bumps. Whatever it is sounds like metal and at first I thought it was something loose in the engine bay (imagine a bolt rolling across metal sort of sound), but after reading some threads on here it could be the sway bar bushing.

I have been around the car pressing all 4 corners of the suspension and am unable to reproduce the noise, therefore I don't think the suspension is at fault.

I've checked around the car for anything loose as best I can but I've found nothing.

The noise only seems to be from the left hand passengers side and only happens on bumps/drains etc...

The noise isn't very loud but it's enough to cause pedestrians to have a glance and can be fairly embarrassing.

Any ideas? Should I go for the DIY greasing of the sway bar bushing?

Yidney

I think it is very unlikely that the sway bar bushings could make a noise like that. How many miles on the car? There could be a number of things the could make the sound (hard to say without being able to hear the sound). Pressing on the car may well not be enough to induce a noise. Could be something like a worn ball joint, a worn end link, a defective strut mount or something harmless like a loose belly pan, brake shield, or clamp holding some fluid line. Just too hard to say without being able to hear it, but sway bar bushings would be low on the list of possibilities.

Rudeney

If you can reproduce the sound in the garage, get a mechanic's stethoscope to pinpoint the source. I once had a noise I though was the sway bar bushing, but it turned out to be the torque strut bushing. I put the front end on jack strands, then used my jack under the tire to "bounce" it so I could hear the noise.

DroolinFool

Thanks for the responses so far guys

Local indy yesterday thinks he has identified this as the suspension ball joint, so I'll get that replaced shortly and see if it resolves the noise or not.

Patton001

I don't think I have ever hears a sound made by a ball joint that I would describe as a "clang". I have heard popping, bumping and knocking but not clang.

Can you isolate it from front and rear? Does it clang when the front tires go over a bump vs when the rears do?

DroolinFool

It's definitely the front passenger side.

To be fair the noise is really hard to describe, it's as if something is loose, e.g. imagine driving over a speed bump with one of the metal covers underneath the car loose - it's that sort of noise but seems to be worse when steering left/right.

Indy said that the ball joint looks really warn, so it'll need replacing anyway, but I'm open to other suggestions as well

The car has done 120,000 miles but seems in top nick otherwise apart from this annoying noise!

Yidney

Did you have the mechanic drive it? He ought to know from experience what it might be.

DroolinFool

He has driven it but admitted it was difficult to pin point.

All I know is;

• It's definitely worse on bumps/drains (suspension related?)
• It can be faintly heard when turning the wheel full lock left/right (but sounds more so like a rubbing/grinding) under these circumstances
• The noise seems metal and is sort of a clang/knocking

I'll let them replace the ball joint initially as this seems like it'll need doing quickly anyway, hopefully in the process of doing this they'll either fix it (if it is indeed that) or identify it if it's something else entirely.


The indy says that these problems are difficult to diagnose due to how well put together the cars are.

Rudeney

Replacing the ball joints means replacing the control arms (i.e. the cross struts and torque struts). At 120K miles, I highly recommend that. The torque strut bushing where it mounts to the frame is fluid-filled and by now, it has surely failed. This can cause noises, but also put the suspension geometry out of spec.

DroolinFool

Thanks for this good to know I'm on the right path going ahead with this.

Yidney

At 120k you are on the right path replacing nearly anything on the suspension if it has not been done. Just take it one step at a time. Have him do a good inspection front and rear of the suspension when he does that repair.

DroolinFool

Little bit more info after spending the last 2 days looking into it more;

The noise is definitely more of a rattle and as far as I can tell is definitely the left side of the car front-mid but not the rear.

I'm still getting the left front side ball joint replaced this week, however I'm somewhat concerned the noise I'm hearing isn't a ball joint.

I've been under the car (as best I can) this morning checking all the panels are secure and not loose. I've also applied grease as best I can do the sway bar bushings (plumbers grease) - though the bushings seem to be in good health and I assume have been replaced before I got the car.

I'm starting to worry after reading on here that this rattle may actually be the cats - HOWEVER I would assume that if it was the cats then the rattle would be continual and not just intermittent over bumps/rough surfaces?

EDIT: Just been under the car and tapped all sections of the exhaust system that aren't under cover (so most of it except the front) and no rattles.

I've also been applying pressure to all 4 corners of the suspension again - no rattles or noises

I've tried pulling/tapping most of the rods/connectors behind the front wheels and again, nothing feels loose or has any sort of tapping noise.

This is really driving me up the wall now, it's such a nice car and this noise is letting the whole thing down. I'm 100% sure this isn't inside the car as you can only hear it with the windows down.

Sometimes it's a faint rattle, sometimes it's loud - I've seen pedestrians do a double take as the car drives past wondering what the noise is.

Any advice is appreciated, hopefully it's the ball joint but I'm seriously thinking it may not be.

Patton001

From your description is sounds more metallic clanging/ringing than hard bumping which would make me want to look at heat shields, brake backing plates etc. If you don't have a jack to safely get the car off the ground and up on jack stands in your garage ask the mechanic if you can poke around while he has it on the lift. He will probably say no as his insurance would kill him if you got hurt but its worth a try. One of my cars had a broken rubber exhaust hanger at one time and the exhaust pipe would hit the rear axle when I hit a bump. There are just too many variables for an educated guess. It just needs to be tracked down from below or under the hood.

Yidney

Were you reaching under there or do you have ramps? Unless the clamps on your bushings are loose, it is not those. If your indy really can't track down a noise loud enough to make people turn their heads, you might need a new indy. Seriously. But nobody can really do more than guess anymore. Just too many possibilities. All I can say is that generally a suspension noise sounds different than something loose like a panel or hose clamp or brake backing plate. Hard to put into words exactly, but those types of things have a "lighter" sound. Not necessarily lower volume, but you can just sort of tell they are a lighter piece that is just not tight and being rattled vs. something in the suspension that sounds like it's under a couple thousand pounds of load. Hard to explain exactly. And partly it depends on the conditions that can induce it. You mentioned the noise while turning? While stationary or only moving? Does it have to hit a bump to to make the noise while turning, or just be turning? While stationary could be strut mounts, while moving could be CV joints. But neither is what I would call a metallic rattle. More of a grinding/clicking. If you are going straight, how much of a bump does it take to induce it? Does the suspension have to compress? Or will it do it if you just hit the little tar strips where cracks in the surface were repaired? If the suspension needs to be compressed, the more likely it is suspension related. But if small things that just rattle the car cause it, then the more likely it is something loose.

DroolinFool

Thanks for the reply.

When turning it's only whilst moving, it does not make the rattle when standing still.

I've been unable to reproduce the noise when stationary at all, via tapping things with my hand, pushing the suspension etc...

I don't have a ramp though so there's only so much DIY "testing" I can do

Small bumps will cause it to rattle, even just drains in the road or uneven road surfaces (and we have an awful lot of them in the UK!). The suspension hardly has to compress. If I'm driving on a smooth road I can't hear it.

Rudeney

I once had a horrible noise from the front end of my ML320 - like oyurs, bad neough that it turned heads of onlookers. It would only make the noise when moving, and turning a corner, and then only when it was "damp" outside - not raining, but not dry, just damp, like after a rain. It turned out to be a loose spring on the hood latch, but before I found it, the dealer replaced the entire front suspension trying to chase it down. My point is, noises can be really hard to find and are not always something major. A good tech will have mics they can place on the car to check for where the noise originates.

DroolinFool

Thanks for all the help everyone - this has been officially diagnosed today as a loose pin on the rear break discs!

Who would have thought!

Just thought I'd update the thread incase anyone else gets this annoying rattle!

Yidney

Figured it would turn out to be something minor. And I'm not even 100% sure what that is since I've yet to pull the rotors on this car - running the same pads for 5 and a half years.